You can also try flea markets and garage sells for old sets that may be missing pieces for a good deal on bricks.

The manual I want to buy has a notice that not all of the bricks in the manual can be found on LEGO.com. Why is that?

LEGO® has been around a long time and from time to time they will discontinue making a certain brick. They also don’t make every brick in every color (especially the transparent colors). So unfortunately our instructions may include discontinued bricks. We are working hard to update the instructions but some times it’s hard to find a good substitute.

Hopefully you can use your creativity to find bricks that would substitute for the ones that are unavailable. Otherwise, try eBay it’s a good place to find bricks that are no longer available on LEGO.com. Most bricks and most colors can be found on eBay.